1.Field of the Invention
The present invention relates to an RFID (Radio Frequency Identification) tag which exchanges information with an external device in a non-contact manner. Note that among those skilled in the art in the technical field of the present application, the “RFID tag” as used in the present specification is regarded as an internal component (inlay) for the “RFID tag” and so it may be referred to as an “inlay for an RFID tag”. Alternatively, this “RFID tag” may be referred to as a “wireless IC tag”.
2.Description of the Related Art
Various types of RFID tags that exchange information with an external device, typically represented by a reader/writer, in a non-contact manner using radio waves have been proposed in recent years (for example, see Japanese Patent Laid-Open No. 2000-310226, Japanese Patent Laid-Open No. 2000-200332, and Japanese Patent Laid-Open No. 2001-351082). An RFID tag in which a circuit chip and a radio wave communication antenna pattern are mounted on a base sheet made of plastic or paper has been proposed as one type of such RFID tag. This type of RFID tag is designed to be used in a mode in which the RFID tag is attached to an article and identification of the article and the like can be performed by exchanging information relating to that article with an external device.
FIG. 8 is a view that illustrates an example of an RFID tag.
Part (a) of FIG. 8 is a top view of an RFID tag 800 as one example of an RFID tag, and part (b) of FIG. 8 shows a cross section along a line of cutting plane H-H of the RFID tag 800 as shown in part (a).
The RFID tag 800 shown in FIG. 8 consists of a long base 801 that is formed with PET film, a communication antenna 802 that is wired along the lengthwise direction on the base 801, a circuit chip 803 that is electrically connected to the antenna 802 and conducts radio communication via the antenna 802, and an adhesive 804 that adheres and fixes the circuit chip 803 to the base 801.
The circuit chip 803 constituting the RFID tag 800 can carry out radio communication with an external device via the antenna 802.
A wide range of usage modes including the usage mode described above can be considered for this kind of RFID tag. However, in the case of a usage mode in which the RFID tag is attached to an article that changes shape easily, such as clothing, a bending stress is applied to the circuit chip 803 because the circuit chip 803 is resistant to bending in comparison to the ease of bending of the base 801, and thus one major problem is that the circuit chip 803 breaks or the circuit chip 803 becomes unstuck from the base 801. Consequently, the following technique has already been proposed as one example of a technique for reducing the bending stress applied to the circuit chip 803.
FIG. 9 is a view showing one example of a conventional technique for reducing a bending stress that is applied to the circuit chip 803.
Part (a) of FIG. 9 is a top view of an RFID tag 900, and part (b) of FIG. 9 shows a cross section along a line of cutting plane J-J of the RFID tag 900 as shown in part (a) in a state in which the RFID tag 900 is bent.
In FIG. 9, components that are equivalent to components shown in the FIG. 8 are denoted by the same symbols as in FIG. 8, and a duplicate description of these components is omitted below.
The RFID tag 900 shown in FIG. 9 is provided with a reinforcing member 901 made of fiber-reinforced resin that covers the upper part of the circuit chip 803. The reinforcing member 901 is adhered and fixed to the base 801 with a thermosetting adhesive 902 that embeds the circuit chip 803.
As shown in part (b) of FIG. 9, according to this RFID tag 900, changes in the shape of the RFID tag 900 are prevented from reaching the vicinity of the circuit chip 803 by the reinforcing member 901 that is formed of a hard substance, namely fiber-reinforced resin, and thus the bending stress applied to the circuit chip 803 is reduced.
However, in the RFID tag 900 shown in FIG. 9 there is a problem that bending stress is concentrated at a part of the adhesive 902 that adheres and fixes the reinforcing member 901 to the base 801 where an edge section that protrudes from the reinforcing member 901 intersects with the antenna 802, resulting in a risk of the antenna 802 becoming disconnected.